Apparently invented by Seluyanov, an athletics coach. The idea is to stop the rep short of dead point. For example, when doing biceps curls don't extend your elbows completely at the bottom and don't flex them to the very top; instead, maintain constant tension throughout the rep and the whole set. Pretty much any other exercise can be done this way - dips, chins, triceps extensions, bench and what not.

Some claim this way is safer - blood pressure and all - I think it's nonsense. In any case, there is no research on any aspects of this method. However, I find it a good way to fuck up the muscles. No harm incorporating it into a cycle now and then. Video below demonstrates it - 3:50 and so on.

This was kind of a thing for a while in the late 90s, early 2000s with Schroeder, DB Hammer, Kelly Baggett, Thibideau, etc. 'Oscillatory training', or 'oscillatory isometrics', or something like that. I thought it was fine as a once-in-a-while tool.

The idea behind this method is to maintain uninterrupted tension of the muscle that's being worked, and it achieves it well. Just try it, fuckers, before commenting. Good start would be bodyweight dips, slowly, without locking out at the top and not going down to the complete relaxation point. Scull crushers without extending the elbows completely, so that arm extensors stay under tension. More of hypertrophy tool, but I don't see why it cannot be classed as "same but different"

As Boris said, good stuff for from-time-to-time use. Like plyometrics, heavy partials, deficits, unilateral work, pressing from sticking points and so fucking on. Not one of the best. Of course, diminishes flexibility to the point of inability to pick a nose. Use a pencil or a door handle, motherfuckers.

However, looking at the dude in the video who claims to be using it - among other things - I believe it has its place.